Glycerol dichlorhydrin



' and, furthermore, that g Patented Apr. 14, 1942 2,279,509 GLYCEROL' DICHLORHYDRIN Harold R. Slagh, Midland, Mich., assignor to The Dow Chemical Company, Midland, Micln, a corporation of Michigan No Drawing. Application July 20, 1939,

Serial No. 285,582

Edgar C. Britton and 11 Claims.

This, invention concerns the use of organic solvents in the purification of glycerol dichlorohydrin.

When glycerol is reacted with hydrogen chlo ride in the presence of a suitable catalyst such as acetic acid to form glycerol dichlorohydrin and 2 molecules of water, the known processes either allow the water of reaction to accumulate in the reaction zone or drive the water out of the reaction mixture by conducting the reaction at elevated temperatures, 1. e., approximately 120 C. or higher. If the water of reaction be allowed to accumulate in the process, there is obtained on fractional distillation of the mixed reaction product-a substantial fraction composed of water, hydrogen chloride, acetic acid and glycerol dichlorohydrin. If water is distilled from the reaction zone at elevated temperatures during the reaction, considerable quantities of glycerol dichlorohydrin, acetic acid, and hydrogen chloride are carried out therewith to form a similar corrosive mixture. Losses of glycerol dich1orohydrin in the above aqueous fractions are considerable. The literature describes several methods for the partial recovery of dichlorohydrin therefrom which involve complicated distillation methods and/or neutralization of said acid fractions with soda ash or similar .alkalies. It has.

been found impossible to separate-more than a small portion of dissolved dichlorohydrin product from these solutions by distillation, and while neutralization of the corrosive mixtures with soda ash, etc., accomplishes a better separation than does distillation, glycerol dichlorohydrin has a considerable solubility in water and salt solutions, and the method fails in recovery of a substantial portion of the desired product. Furthermore, neither of the above procedures is particularly adapted to produce an anhydrous product, considerable amounts of water being present in glycerol-dichlorohydrin recovered from aqueous hydrogen chloride solutions according to the known methods.

We have discovered that by extracting the above-described glycerol dichlorohydrin-containing acid fractions with a liquid chlorinated aliphatic hydrocarbon, the major proportion of the desired dichlorohydrin product may be recovered, fractional distillation of the extract so obtained yields essentially anhydrous glycerol dichlorohydrin. The essential characteristics of the liquid chlorinated aliphatic hydrocarbons which render them particularly suitable in the extraction of glycerol dichlorohydrin are that (1) they have a high extraction coefiicient for glycerol dichlorohydrin in aqueous acid solution; that is, the solubility of glycerol dichlorohydrin in such solvents is such that the major proportion of the dichlorohydrin product is conveniently extracted'from solution in the water or aqueous hydrochloric acid, (2) they do not extract appreciable quantities of hydrochloric acid from the treated corrosive mixtures, (3) they are relatively immiscible with water,- (4) they are readily separable from the extracted aqueous solution as by decantation and from glycerol dichlorohydrin as by distillation, and (5) they are relatively inert; that is, they do not tend to react with glycerol dichlorohydrin in hydrochloric acid or to be hydrolyzed during the extracting and distilling steps. The chlorinated aliphatic hydrocarbons with which this invention is particularly concerned are those which are liquid at ordinary temperatures and which'contain not in excess of '6 carbon atoms.

In carrying out our process. the water or aqueous hydrochloric acid solution of glycerol dichlorohydrin which may or may not contain dissolved acetic acid or other reaction catalyst is intimately contacted with the solvent, the resulting mixture allowed to layer out, and the glycerol dichlorohydrin-containing solvent layer separated from the aqueous residue. If necessary, several extractions of the aqueous glycerol dichlorohydrin solution may be made, after which the various extractions may conveniently be comebined and the glycerol dichlorohydrin separated therefrom by fractional distillation. Small amounts of water present in suchcombined extracts are removed therefrom as a steam distillate along with portions of the solvent during the first stages of the fractionation, the glycerol dichlorohydrin being recovered in substantially anhydrousform as generally a higher-boiling fraction. If desired, the extract may be treated withsmall amounts of sodium carbonate or other suitable alkaline material prior to the distillation step to remove traces of acetic acid and/or hydrochloric acid which may be present in said extract.

The following examples illustrate the use of certain representative liquid chlorinated aliphatic hydrocarbons in the carrying out of our invention, butare not to be construed as limiting the same:

- Example 1 38.4 pounds of glycerol and 1.75 pounds of glacial acetic acid were mixed together in a glass reactor and gaseous hydrogen chloride slowly introduced thereinto, the reaction temperature recovery of 39.2 grams of desired product or 78.4 per cent of theory.

While the foregoing examples describe the multiple extraction of acid fractions to recover glycerol dichlorohydrin therefrom, in plant operation the amount of extraction solvent required approximately theoretical chlorine content. The 10 extracted with a relatively small volume of sol- 38.1 pounds of crude glycerol dichlorohydrin vent, small portions of which are continuously product remaining in the reaction flask was then withdrawn from the extraction zone into a suitfractionally distilled under reduced pressure, able fractionation apparatus, wherein the lowwhereby there was obtained 3 pound of a lowboiling solvent and traces of water present in the boiling aqueous acid fraction. 310 pounds of sub- 5 extract are distilled oil and returned to the exstantially' pure glycerol dichlorohydrin, 3.2 traction zone, glycerol dichlorohydrin being repounds of glycerol rnonochlorchydrin, and 3.6 tained-in the body of the distilling apparatus as pounds of high-boiling residue. The 31.0 pounds a residue. When no additional glycerol dichloroof desired product represented a yield of "only hydrin can be removed from the aqueous acid 57.5 per cent of theoretical based on the glycerol fraction the extraction operation is suspended used as a starting material. and the accumulated still residue of glycerol di- The 30.9 pounds of acid fraction recovered as chlorohydrin product is fractionated to obtain a distillate from the reaction zone during the the desired compoundin substantially pure form hydrogen chloride addition was extracted three In plant operation employing ethylene chloride times with ethylene chloride. Each extraction as the solvent an aqueous acid fraction originally required between 6 and 8 pounds of solvent and containing 25 per cent by weight of glycerol dithe total weight of ethylene chloride employed chlorohvdrin was found, after extraction, to conwas 20 5 pounds. The extracts so obtained were tain only 3 per cent by weight of said compound combined and fractionally distilled, whereby an dissolved therein. additional 8 1 pounds of substantially anhydrous Among other solvents which have been found glycerol dichlorohydrin was recovered The total satisfactory as extractants in our process are yield of product was, therefore, 39 1 pounds of y n chloride, normal hexyl Chloride. mal glycerol dichlorohydrin, representing a theoretimyl l ride. chloroform etc. If desired mixcal yield of 72 5 per cent. 20 25 pounds, approxir -S I" tW m l n m y be mployed. mately 99 per cent of the ethylene chloride used p butyl chloride-carbon tetrachlorid in the extraction was recovered and re-utilized p y n de-ethyle hl r e hylene in subsequent runs. chloride-carbon tetrachloride mixtures, etc. Emmple 2 Such combinations of solvents are of particular value where it is desired (1) to reduce fire hazard In a similar manner. 253 grams of an acid 40 and flammability of the reaction mixture, and fraction containing 63.2 grams of dissolved glyc- (2) to obtain some particular specific gravity for erol dichlorohydrin and 63 2 grams of hydrogen the extracting solvent in order to facilitate sepchloride was successively extracted with 151 5 aration of said extractant from the aqueous acid 145.5, and 149 5 gram portions of 1 1,2-trichlorofraction. ethane, whereby 28.2, 15.2, and 6.2 grams, respec- The present application is a continuation-intively, of dichlorohydrin product was removed part of our co-pending and prior filed application from aqueous solution. Fractional distillation of Serial No. 100,211. filed September 10, 1936. the combined extracts resulted in the isolation Other modes of applying the principle of u of 49 6 grams of substantially anhydrous glycerol invention may be employed instead of those exdichlorohydrin, which represents a recovery, of 50 plained, change being made as regards the meth- 7 P r cent f h ods herein disclosed, provided the step or steps Emmple 3 stallion; by; any of thei1 follow claims or the e v en An acid fraction comprising 49.5 grams oi eglployedn 0 any sue stat step or step be glycerol dichlorohydrin and 148.5 grams of a we therefore particularly pomt out and 33% per cent equeous hydrochloric acid solution tmcuy claim as our invention: was subjected to three extractions with ethylene 1. In the recovery of my c er 01 dicmomhydrm chloride. The 126.0, 122.0, and 124.5 gram porfrom an a I queous solution comprising the sam tions of solvent employed in the extraction rethe Ste hi h is; ti moved 23.0 11 5 and 5.0 grams of dichlorohydrin p5 w c a 0 extrac 18 said solution with ethylene chloride. product, respectively, from the aqueous solution. Combination of the above extracts and fractional In the F of glycerol y rin distillation under reduced pressure resulted in 1mm an aqueous Solution comprising the same, the isolation of 39 5 grams of substantially anthe steps which consist f extracting said soluhydrous and acidqree g1ycer1 dichlorohydrin tion with ethylene chloride, and thereafter sepwhich represents a recovery of 80 per cent of Mating he glycerol dichlorohydrin from the theoretical. ethylene h r de y fractional distillation.

Ekample 4, e recovery of glycerol dichlorohydrin from an aqueous hydrochloric acid solution com- Extraction of 200 grams of an acid fraction prising the same. the step which consists of exthereafter separating the glycerol dichlorohydrin tional distillation, whereby glycerol (1101110170 from the ethylene chloride. hydrin is obtained in substantially anhydrous 5. In the extraction of glycerol dichlorohydrin condition. from an aqueous hydrochloric acid solution com- 9. In the recovery of glycerol dichlorohydrin prising the same, the steps which consist of inti- 5 from an aqueous solution comprising the same, mately contacting said solution with ethylene the steps which consist of extracting said soluchloride, withdrawing the resulting solventtion with an alkylene chloride selected from the glycerol dichlorohydrin extract from the extracgroup consisting of ethylene chloride and propyltion zone, and thereafter removing residual-water ene chloride, and thereafter separating the glycand ethylene chloride from said extract by fraceroldichlorohydrin from such solvent by frac-, tional distillation, whereby glycerol dichlorotional distillation..

hydrin is obtained in substantially anhydrous 10. In the recovery of glycerol dichlorohydrin condition. from an aqueous hydrochloric acid solution com- 6. In the recovery of glycerol dichlorohydrin prising the same, the step which consists of exfrom an aqueous solution comprisingthe same. tracting said solution with an alkylene chloride the step which consists of extracting said soluselected from the group consisting of ethylene tion with propylene chloride. chloride and propylene chloride.

'7. In the recovery of glycerol dichlorohydrin 11. In the extraction of glycerol dichlorohydrin from an aqueous hydrochloric acid solution comfrom an aqueous hydrochloric acid solution comprising the same, the steps which consist of exprising the same, the steps which consist of intitracting said solution with propylene chloride mately'contacting said solution with an alkylene and thereafter separating the glycerol dichlorochloride selected from the group consisting of hydrin from the propylene chloride. ethylene chloride and propylene chloride, with- 8. In the extraction of glycerol dichlorohydrin drawing the resulting solvent glycerol dichioro-V from an aqueous hydrochloric acid solution comhydrin extract from the extraction zone, and

prising the same,- the steps which consist of intithereafter removing, residual water and solvent mately contacting said solution with propylene from said extract by fractional distillation wherechloride, withdrawing the resulting solventby glycerol dichlorohydrin is obtained in substanglycerol dichlorohydrin extract from the extractially anhydrous condition.

tion zone, and thereafter removing residual water EDGAR C. BRITTON. and propylene chloride from said extract by frac- HAROLD R. SLAGH. 

